Albertans’ sources of drinking water come from two places, surface water and groundwater accessed through wells; but the two have traditionally been managed as being separate.
Now scientific research is showing that surface and groundwater sources are interconnected and should be managed as an entire watershed to ensure principles of sustainability are achieved.
University of Calgary professor Masaki Hayashi was in Canmore earlier in July to provide a talk on the issue of sustainable groundwater from the watershed perspective during a Canmore Museum and Geoscience Centre open house.
“So traditionally (surface and groundwater) were managed completely separately, with different people with different expertise looking at these two different resources,” said Hayashi. “But in the past decade, we are coming to understand these two resources are actually connected, so we need to see it as a single resource and manage it from the perspective of a watershed.
“All the surface water you see in rivers and lakes, they were once groundwater and they may become groundwater again,” Hayashi added. “They are going back and forth and starting at the headwaters of the mountain regions.”
He said groundwater is a very important player in the alpine water cycle. A study of Lake O’Hara showed that more water was flowing out of the lake than went into it from other streams or precipitation. The difference means that the small alpine lake is being fed by groundwater sources.
“So this is an example of groundwater feeding lakes and rivers at the very top of the watershed and there are similar things happening in the foothills,” he said.
Hayashi said Canmore is in an interesting situation when it comes to drinking water supply because it uses surface water and groundwater at the same time.
The Rundle Forebay towards Spray Lakes is a source of drinking water that is surface water, while the other source is two wells in the valley bottom that tap into a large underground aquifer.
As a result, water from the tap in the community is a blend of both and in total, Canmore uses two million cubic metres a year of fresh water through that system. Hayashi said as a per capita amount that works out to 530 litres a day per resident. That is more than double the world average of 200 to 250 litres.
What makes up for that added amount of water use is the fact that on any given day there are far more people than the 12,000 permanent residents recognized in the federal census.
In the Canmore Kananasis region, water use has increased dramatically over the past few decades, according to Hayashi.
A 2002 Alberta Environment report shows water licence holders can be broken up to include industrial uses (28 per cent), ski hills (23 per cent), municipal water licences (19 per cent) and golf courses (17 per cent).
Hayashi said it is possible to see the interaction between Canmore’s aquifer, or groundwater, with the river system. Spring Creek, for example, originates in the middle of town from groundwater and flows into the Bow River.
“So this active exchange is really important in understanding the groundwater in the ecosystem and the way this type of groundwater should be managed in aquifers,” he said. “There are several mechanisms at different scales that helps this surface water-groundwater interaction.”
Hayashi said there are two fundamental rules that are generally true. The first is that the water table is a subdued replica of the landscape. In other words, he said groundwater is higher under hills and mountains and lower under bodies of water.
The second, is that groundwater flows from high to low. Hayashi explained that groundwater levels recharge at higher elevations and discharge into streams and lakes.
“So with these two things together we can come up with a framework for sustainable water resource management,” he said. “Again, this is a concept of water balance.”
There is also an important connection when stormwater from rain events is added into the equation, when it comes to ground and surface water interaction, said Hayashi. However, he added that on average summer rain is absorbed by plants and it is the snow melt or thaw in the spring that significantly recharges groundwater levels each year.
He said stormwater can still permeate the ground during rain events and can become groundwater in mountain environments.
“The forested environment is so permeable to rain and snowmelt goes into the soil and this water becomes groundwater,” Hayashi said.
The connection between recharge and discharge is key to determining water levels in any watershed.
Hayashi said water management needs to recognize groundwater as part of the watershed and determine sustainable pumping rates using a watershed-based approach. He said long-term monitoring is essential to ensuring water is being managed appropriately.
For Canmore, he said, it is important to look at the exchange of water in terms of recharge and discharge between groundwater and the Bow River.
“There is a very close connection between groundwater and river water in this particular location,” he said.
